sqlite3: bug with monotone

Corinna Vinschen corinna-cygwin@cygwin.com
Tue Jun 4 08:48:00 GMT 2013


On Jun  3 11:36, Warren Young wrote:
> On 6/2/2013 04:31, Corinna Vinschen wrote:
> >I dropped the F_MDLCK idea. Instead I implemented a specific fcntl code
> >to switch to mandatory locking on a file descriptor:
> >
> >   fcntl (fd, F_LCK_MANDATORY, 1);
> 
> Could you add an O_MAND open(2) option as well to turn on the same
> feature?  This will avoid a race condition.

If you call F_LCK_MANDATORY right after open in the opening routine,
there won't be (much of) a race.  I know what you mean (it's the
O_CLOEXEC dilemma) but is it really that important in terms of locking?

> As I see it, the test will proceed in several stages:
> 
> 0. I patch SQLite and run it against both .18 and your snapshot, and
> strace it to verify that fcntl(fd, 0x99, 1) is called and returns 0
> with the snapshot and returns -1 with errno == EINVAL for .18.  Both
> count as "success" so we don't have to require .19.
> 
> 1. I upload it, and Achim and Yaakov try it and see if this new
> build satisfies their use cases.

Well, we will have more than one round of testing, apparently...(*)


Corinna


(*) http://cygwin.com/ml/cygwin/2013-06/msg00042.html

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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